ATSR

ATSR consists of two instruments, an Infra-Red Radiometer (IRR) and a Microwave Sounder (MWS). On board ERS-1 the IRR is a four-channel infra-red radiometer used for measuring sea-surface temperatures (SST) and cloud-top temperatures, whereas on board ERS-2 the IRR is equipped with additional visible channels for vegetation monitoring. The MWS is a two channel passive radiometer.

GOME

GOME, a nadir-scanning ultraviolet and visible spectrometer for global monitoring of atmospheric Ozone, was launched on-board ERS-2 in April 1995.

Since summer 1996, ESA has been delivering to users three-day GOME global observations of total ozone, nitrogen dioxide and related cloud information, via CD-ROM and internet.

A key feature of GOME is its ability to detect other chemically active atmospheric trace-gases as well as aerosol distribution.

MWR

The main objective of the microwave radiometer (MWR) is the measurement of the integrated atmospheric water vapour column and cloud liquid water content, as correction terms for the radar altimeter signal. In addition, MWR measurement data are useful for the determination of surface emissivity and soil moisture over land, for surface energy budget investigations to support atmospheric studies, and for ice characterization.

PRARE

The Precise Range And Range-Rate Equipment PRARE is a compact, space-borne, two-way, two-frequency microwave satellite tracking system that is in routine operations onboard the second European Remote Sensing satellite ERS-2 since May 1st, 1995.

RA - Radar Altimeter

The Radar Altimeter is a Ku-band (13.8 GHz) nadir-pointing active microwave sensor designed to measure the time return echoes from ocean and ice surfaces.

Functioning in one of two operational modes (ocean or ice) the Radar Altimeter provides information on significant wave height; surface wind speed; sea surface elevation, which relates to ocean currents, the surface geoid and tides; and various parameters over sea ice and ice sheets.

SAR

The images are transformed into directional spectra providing information about wavelength and direction of wave systems.

Automatic measurements of dominant wavelengths and directions will improve sea forecast models, but the imagettes can also show the effects of other phenomena, such as internal waves, slicks, small scale variations in wind and modulations due to surface currents and the presence of sea ice.

WSCATT

The purpose of the Wind Scatterometer is to obtain information on wind speed and direction at the sea surface for incorporation into models, global statistics and climatological datasets.

It operates by recording the change in radar reflectivity of the sea due to the perturbation of small ripples by the wind close to the surface.

This is possible because the radar backscatter returned to the satellite is modified by wind-driven ripples on the ocean surface and, since the energy in these ripples increases with wind velocity, backscatter increases with wind velocity.